Smallfoot is less likely to conjure up images of dinosaurs than Littlefoot. I’m not sure that ‘foot’ was a particularly over-represented surname element. The only one I can think of is Proudfoot.
The list of names that Bilbo rattles off during his birthday speech include Baggins, Boffin,Took, Brandybuck, Grubb, Chubb, Burrows, Hornblower, Bolger, Bracegirdle, Goodbody, Brockhouse, Proudfoot, and Sackville-Baggins. Additionally we know of Gamgee, Maggot, Cotton, Sandyman, Longbottom, Gardner, Banks, (probably more I can’t find at the moment) and what is apparently a common-enough-not-to-stand-out name of Underhill.
Given that you’re going for a family name, Smallfoot sounds like this family must be remarkably notable for having smaller than average Hobbit feet, not just the one character. Which would definitely be a trait worthy of note among Hobbits.